Town Car V8-4.6L VIN V Flex Fuel (2006)
Air Bag Control Module: Description and Operation
RESTRAINTS CONTROL MODULE (RCM)
WARNING: The restraints control module (RCM) orientation is critical for correct system operation. If a vehicle equipped with an air bag
supplemental restraint system (SRS) has been involved in a collision in which the center tunnel area has been damaged, inspect the mounting
and bracket for deformation. If damaged, a new RCM must be installed whether or not the air bags have deployed. In addition, make sure the
area of the RCM mounting is restored to its original condition.
NOTE: When a new RCM is first installed in the vehicle, module configuration must be carried out. The diagnostic trouble code (DTC) B2477 will be
stored in the RCM memory (continuous fault) and will flash lamp fault code (LFC) 54 (or higher priority code if one exists) on the air bag indicator. The
DTC B2477 cannot be cleared from memory until RCM configuration has been carried out.
The restraints control module (RCM) is mounted on the center tunnel under the instrument panel. The RCM carries out the following functions:
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Signals the inflators to deploy the air bags in the event of a deployable crash.
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Activates the safety belt retractor pretensioners to remove slack from the safety belt.
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Monitors the air bag SRS for faults.
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Illuminates the air bag indicator if a fault is detected.
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Receives information from the front and side impact sensors.
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Sends safety belt buckle status to the instrument cluster for safety belt lamp and belt-minder.
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Flashes the air bag indicator to indicate the lamp fault code (LFC) detected.
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Communicates through the data link connector (DLC) the current or historical diagnostic trouble codes (DTCs).
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Signals the instrument cluster to activate a chime if the air bag indicator is not available and another SRS fault exists.
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Contains an internal safing sensor which is not serviced separately.
The RCM monitors the SRS for possible faults. If a fault is detected while the ignition switch is in the RUN position, the RCM will illuminate the air bag
indicator located in the instrument cluster.
When the ignition is cycled (turned OFF and then ON), the air bag indicator will remain lit for 6 seconds and then go out. If an SRS fault exists, the air
bag indicator will then flash the 2-digit LFC. The air bag indicator will flash the LFC 5 times, then it will remain illuminated for the rest of the key cycle.
The RCM will also communicate the current and historical DTCs through the data link connector (DLC), using the diagnostic tool. If the air bag
indicator does not function, and the system detects a fault condition, the RCM will signal the instrument cluster to activate an audible chime. The chime
is a series of 5 sets of 5-tone bursts. If the chime is heard, the SRS and the air bag indicator require repair.
LFCs are prioritized. If 2 or more faults occur at the same time, the fault having the highest priority will be displayed first. After that fault has been
corrected, the next highest priority fault will be displayed.
The RCM includes a backup power supply. This feature provides sufficient backup power to deploy the air bags in the event that the ignition circuit is
damaged in a collision before air bag deployment is activated. The backup power supply will deplete its stored energy approximately one minute after
ignition power is removed from the RCM.
